Ice making refrigeration apparatus



Oct. 25, 1966 c. E. LOWE ICE MAKING REFRIGERATION APPARATUS 5 Sheets-Sheet 1 Filed Sept. 27, 1965 INVENTOR m N m w A G OJLHQMQL QfiARLEs E. Lowe asowfg wuiwflu f Oct. 25, 1966 c. E. LOWE ICE MAKING REFRIGERATION APPARATUS 5 Sheets-Sheet 2 Filed Sept. 27, 1965 INVENTOR Oct. 25, 1966 c. E. LOWE 3,280,585

ICE MAKING REFRIGERATION APPARATUS Filed Sept. 27, 1965 5 Sheets-Sheet 3 e. aw w a a 11lg 5 9 l3" V 220V 1 1 1 E \g e, if 2 COW/P2555016 1o oemvkcwrs 6 547-52 I NVENTOR ATTORNEYS Oct. 25, 1966 c, LOWE ICE MAKING REFRIGERATION APPARATUS 5 Sheets-Sheet 4 Filed Sept. 27, 1965 INVENTOR 35 @3 CHARLES E. LOWE 1966 c. E. LOWE 3,280,585

ICE MAKING REFRIGERATION APPARATUS Filed Sept. 27, 1965 5 Sheets-Sheet 5 INV ENT OR Cl-mzLzs E.LOWE

ATTORNEYS United States Patent 3,280,585 ICE MAKING REFRIGERATION APPARATUS Charles E. Lowe, 609 Harwood Ave., Orlando, Fla. Filed Sept. 27, 1965, Ser. No. 490,453 8 Ciaims. (Cl. 62-347) The present invention relates in general to heat exchange refrigeration systems, and more particularly to refrigeration systems for ice making or cooling purposes which are cycled alternately through a freezing phase and a harvesting or defrosting phase in the operation of the system.

Automatic ice making apparatus involving reversible cycle refrigeration systems have gone into wide commer cial use. In such systems, ice is produced during the normal refrigerating or freezing phase of the apparatus when condensed liquid refrigerant is admitted to the evaporator, and the ice is discharged from the evaporator during the defrosting or harvesting phase when hot gaseous refrigerant is delivered directly from the compressor to the evaporator. Such systems have customarily involved an evaporator having a refrigerant chamber which contains a large volume of liquid refrigerant at the conclusion of the freezing cycle. To accomplish rapid defrosting of the ice from the evaporator by hot gaseous refrigerant and avoid undesirable melting of the ice as distinguished from mere release of the frost bond between the ice and the evaporator ice-forming surfaces, it has been thought that some means must be provided to rapidly dump substantially all of the liquid refrigerant from the evaporator at the commencement of the harvesting cycle and store this refrigerant in a storage tank or another evaporator during the remainder of the harvesting cycle. Obviously the necessity of providing facilities for so handling the liquid refrigerant increases the complexity and cost of the equipment as well as requiring relatively large qantities of refrigerant.

It has been discovered that effective and rapid harvest ing of ice from the evaporator by cycling hot gaseous refrigerant thereto can be achieved without requiring dumping or storing of the liquid refrigerant which remained in the evaporator at the conclusion of the freezing cycle, by introducing the hot gaseous refrigerant into the refrigerant chamber of the evaporator in such a way that the hot gaseous refrigerant is placed in effective thermal exchange relation with the liquid refrigerant throughout the entire height of the body of liquid to quickly vaporize the liquid refrigerant or warm it sufficiently to release the frost bond holding the ice to the iceforming surfaces of the evaporator. Such refrigeration systems have required a number of solenoid valves to effect proper selective control of intercoupling of the components of the refrigeration system to establish the various phases of operation forming the complete cycle of operation of the system. Substantial improvement in the economy of construction and operation of such apparatus is eminently desirable. However, it has been discovered that a far simpler and effective method of producing and harvesting ice may be done by employing the system contemplated by the present invention. Generally this system utilizes a flooded evaporator principle in which no expansion valve is incorporated in the high pressure side of the system and in which no refrigerant is added to the evaporator during the freezing cycle. There is also provided a novel evaporator structure upon which the ice is formed.

While the present invention is applicable to liquid chilling applications, cooled storage room refrigeration and the like applications, it will be described specifically in connection with the automatic production of ice to simplify understanding of the construction and operation of the system.

3,280,585 Patented Oct. 25, 1966 An object of the present invention is the provision of novel ice-making apparatus having a cycle of operation wherein the apparatus is cycled successively through freezing and thawing phases, which is of economical construction and has a novel mode of operation.

Another object of the present invention is the provision of novel automatic ice making apparatus operating automatically through freezing and harvesting phases wherein the components are intercoupled and controlled in a manner effecting a substantial reduction in the number of valves required and therefore in the cost of production of the apparatus.

A still further object of this invention is the provision of a novel refrigeration system utilizing a-fiooded evaporator and one in which the evaporator surfaces upon which the ice forms are of novel construction.

Further aims, objects and advantages of this invention will appear from a consideration of the following description and the accompanying drawings showing for purely illustrative purposes embodiments of this invention. It is to be understood, however, that the description is not to be taken in a limiting sense, the scope of the invention being defined in the appended claims.

In the drawings:

FIGURE 1 is a diagrammatical view of the automatic ice making apparatus constructed in accordance with one preferred embodiment of the present invention;

FIGURE 2 is a vertical section view taken along lines 22 of FIGURE 1;

FIGURE 3 is a vertical section view to enlarged scale taken along lines 33 of FIGURE 1;

FIGURE 4 is a view similar to that shown in FIGURE 1; however, showing the parts more diagrammatically and with the parts broken away in sections;

FIGURE 5 is a horizontal section view taken along lines 55 of FIGURE 4;

FIGURE 6 is a circuit wiring diagram of a form which controls the apparatus shown in the present invention;

FIGURE 7 is a diagrammatic view of a second preferred embodiment of the automatic ice making apparatus constructed in accordance with the present invention embodying slightly different ice making surfaces upon the evaporator;

FIGURE 8 is a vertical section view taken along lines 8-8 of FIGURE 7;

FIGURE 9 depicts a typical form of the ice cubes which are made by the evaporator shown in the second embodiment of the invention and more specifically by FIGURES 7 and 8; and

FIGURES 10 and 11 are fragmentary views similar to the lower portions of FIGURES 7 and 8, showing another embodiment.

Referring to the drawings, wherein like reference characters designate corresponding parts throughout the several figures, and particularly to FIGURES 1-6, the basic components of the ice making apparatus comprise a motor driven compressor 10 having the usual high pressure discharge and low pressure suction ports, a high pressure discharge line 11 leading from the compressor 10 through a conventional oil separator 12 and a manual valve 13 to a condenser-receiver 34, a liquid refrigerant line 15 valved by a manual valve 16 and solenoid valve 17 and leading from the condenser-receiver 14 through a heat exchanger 18 to a distributor 19. Plural outlet conduits 20 extend to the evaporator unit 21 of a construction to be later described and terminate in refrigerant distributor tubes 22 extending vertically downwardly through the top of the evaporator 21 to a point rear the bottom of the evaporator. Suction conduits 23 lead from the upper region of the evaporator 21 into an accumulator 24 serving as a main reservoir for liquid refrigerant, and a suction line 25 extends from the upper region of the accumulator 24 to the shell of heat exchanger 18.

A suction conduit 26 extends from the upper region I of the heat exchanger shell 18 to the suction port of,

the compressor 10, completing the refrigerant circuit.

The accumulator 24 is an insulated tank to prevent or minimize thermal loss to the surrounding air, and includes an inclined oil pan 27 disposed at an intermediate level in the accumulator 24, the lower end of which is connected by conduit 28 having normally closed, timer conpressor 10, sized to limit oil return to such small quantities as will not damage the compressor.

It will be noted that the suction conduits 23 leading from thevupper region of the evaporator 21 to the accumulator 24 terminate in upwardly projecting legs 23 extending above the bottom of the accumulator to a level near the top of the accumulator where vapor phase refrigerant continuously exists and have open upperends, cut for example, on a plane inclined to the vertical axis, to conduct vapor phase refrigerant from the evaporator 21 into the upper zone of the accumulator. The legs 23 also have small orifices 23a in their walls immediately above the bottom of the accumulator in the liquid phase refrigerant zone thereof to admit liquid phase refrigerant from the accumulator into the conduits 23 for gravity return to the evaporator 21. While but two suction lines opening at their lower ends in the end walls of theevaporator 21 adjacent the top thereof are specifically shown in FIGURE 4, it will be apparent that as many such suction lines between the upper region of the evaporator 21 and the accumulator 24 may be provided as are desired to effect proper transfer of liquid and gas phase refrigerant between the evaporator and the accumulator, and that the lower ends of all'the suction conduits 23, or the additional suction conduits, may terminate in the top wall of the evaporator at suitable horizontally spaced intervals.

A suitable water spray header 30 extends about the top of the evaporator 21, which may take the form of a pair of parallel horizontal header pipes 31 spaced outwardly from adjacent surfaces of the evaporator 21 having upwardly directed spray nozzles 32 spaced axially along the header pipes 31, the pipes 31 being joined bya T-fitting to a common water supply pipe 33 leading from a conventional motor driven pump 34 (FIGURE 6).

One physical arrangement of the refrigeration system components diagrammatically shown in FIGURE 4 in an ice-making machine for making crushed ice is illustrated in FIGURES 1 and 2, the components being supported in a convenient and compact manner in a frame 35, having base-forming channel members 36, upright angle irons 37, and top channel members 38, the refrigeration system components being fixed to these frame members and to support members secured therebetween in a conventional manner. One satisfactory form of evaporator 21 in such a crushed ice making machine is that shown in FIGURES 1, 2, 4 and 5, wherein the evaporator 21 is in the configuration of a rectangular solid providing large planiform lateral surfaces 40, 41 of rectangular outline on which the water is sprayed from nozzles 32 to form large, thin sheets of ice (indicated at 42 in FIG- URE 2), these lateral surfaces 40, 41 being spaced transversely by a small distance, for example about one inch, to define a body of very shallow transverse thickness. Preferably, the interior of the evaporator 21. is arranged to provide a plurality of parallel, horizontally spaced, vertically elongated chambers or compartments 43 having their axes disposed in a single vertical plane, the

bottoms and tops of these chambers being in open communication with a bottom manifold chamber 44 and a top manifold chamber 45 formed internally of the evaporator 21. One convenient way to form such internal compartmentation of the evaporator is to assemble the evaporator body from a plurality of hollow rectangular thin walled tubes 46, for example, stainless steel, copper or aluminum tubes of square cross-section having sides one inch or wider, by welding or brazing adjacent sides of the tubes together in series, parallel aligned fashion to provide an assembly as illustrated in FIGURE 5 wherein the sides of the tubes paralleling the axes of the header 31 define the pair of flat planiform'surfaces 4G, 41 of desired area. Another such rectangular tube is employed to provide each of the top and bottom manifolds 44, 45, holes such as the circular holes 47 being formed in one side ofeach of these tubes at appropriate points to be aligned with the axes of the vertical tubes and the apertured sides of these manifold-forming tubes being welded, brazed or otherwise suitably secured to the tops and bottoms of the vertical tubes'toform the evaporator body The ends of'the horizontal, manifoldforming tubes will, of course, be closed by suitable plates of similar material and thickness as the walls of the tubes.

In the crushed ice machine illustrated in FIGURE 1, an ice crusher and conveyor assembly 50 extends below the evaporator 21 over the entire length of the evaporator surfaces 40, 41, and comprise an upwardly opening trough 51 of U-shaped cross section defining a semi-cylindrical bottom portion concentric with the axis of a conveyor screw 52, the periphery of the helical vane portion of which extends very close to the bottom portion of the trough 51. The shaft of the conveyor screw 52 is coupled by a conventional chain and sprocket drive 53 to an electric motor 54, to rotate the conveyor screw 52 in a directionto crush the sheet ice dis-charged from the evaporator surfaces 40, 41 'into the trough'51 and convey the same to the left, as .viewed in FIGURE 1, to an externally accessible end portion of the trough for removal by an attendant or by automatic conveyor means. It will be noted from FIGURE 1 that the conveyor trough 51 is inclined somewhat downwardly, toward the right hand or feed end thereof, and is provided with a drain hole 55 at the lower end toeffect gravity feed of water in the trough to the drain hole 55 for withdrawal into a suitable collecting pan or sump and circulation through pump 34 back to the spray nozzles 32.

The above described refrigeration system operates as a closed loop system cycling through freezing and harvesting phases without the use of any expansion valves or other means for metering liquid refrigerant into an evaporator during the freezing cycle such as is customarily employed. In the present refrigeration system, assuming the evaporator to be properly charged with refrigerant, so that the evaporator 21, the suction lines 23 and the lower portion of the accumulator 24 are filled with liquid refrigerant, operation of the compressor 10, with the solenoid valve '17 closed, will pump down the pressure in the accumulator 24 by-the suction applied to the suction lines 26, 25. This reducing pressure is reflected through the suction lines 23 to the evaporator 21.

Since the solenoid valve 17 in the liquid line 15 is closed,

the evaporator 21 is effectively a closed chamber with no inlet, so that the pressure reduction eflected therein by operation of the vcompressor 16 reduces the pressure in the evaporator to a level where vaporization of the liquid refrigerant in the evaporator 21 (and, of course, in

the suction lines 23 and accumulator 24), takes place,

extracting heat from water sprayed onto the exterior surfaces 40, 41 of the evaporator by the nozzles 32 and converting the film of water to ice which progressively increases in thickness and produces ice sheets on these two evaporator surfaces 40, 41. ness of ice has developed on the evaporator surfaces 40, 41, which may be determined in any of several known When an appropriate thickways, such as by an automatic timer (indicated by the motor and cam 56 indicated schematically in FIGURE 6) or by an ice thickness sensor or other conventional means, the solenoid valve 17 is energized to open the valve 17 and admit liquid refrigerant from the condenser-receiver 14, in which refrigerant is condensed to liquid phase and stored during the freezing cycle, through the line 15, heat exchanger 18, distributor 19, conduits 20 and distributor tubes 22 to the bottom manifold chamber 44 of the evaporator 21. Of course, during the freezing cycle, the liquid refrigerant in the interior or hollow spaces in-the vertical chambers 43 of the evaporator, as well as in the tubes 22 and to some extent in the accumulator 24, becomes largely converted to vapor phase refrigerant. Upon opening of the valve 17 to establish the harvesting cycle, these chambers 43 then rapidly fill wit-h liquid refrigerant supplied through the liquid line 15. It will be observed that the opening of valve 17 in the line 15 effectively opens the inlet to the evaporator, rapidly increasing the pressure in the evaporator and in the accumulator 24 to effect recondensation of vapor refrigerant which remained therein at the beginning of the harvesting cycle. The liquid refrigerant supplied through the line 15' is warmed somewhat by heat exchange in the exchanger 38 with the vapor phase refrigerant being drawn through suction conduits 25 and 26 to the compressor 1%). The rejection of heat to the ice sheets on the surfaces of the evaporator by recondensation of vapor phase refrigerant and by filling of the evaporator with the somewhat warmed liquid refrigerant through line 15 rapidly thaws the frost bond between the ice sheets and the evaporator surfaces 40, 41 permitting gravitational discharge of the ice sheets into the crusher-conveyor assembly 59. The ice is promptly disintegrated into crushed ice by the helical vanes of the conveyor screw 52 and is propelled to the externally accessible end of the conveyor trough 51. After the short harvesting cycle, which only lasts for a sufi'icient duration to refill the evaporator with liquid phase refrigerant and thaw the frost bond holding the ice sheets to the evaporator surfacse 40, it, the timer 56 or other cycle control mechanism returns the system to freezing mode by closing the solenoid valve 17, whereupon the previously described cycle repeats itself.

It will be observed that vaporized oil entrained with the liquid refrigerant supplied to the evaporator 21 migrates to the accumulator 24 and collects in the oil pan 27 as liquid phase oil. Periodically, the solenoid valve 29 is opened by a suitable timer to admit the oil collected in the pan 29 through the conduit 28 to the heat exchanger 18, where some of the liquid oil may vaporize and be withdrawn to the compressor it) through suction line 26 or the liquid oil collects in the bottom of the heat exchanger 18 and is admitted in small amounts through orifice 26a into suction line 26 to return to the compressor 19.

The Water pump 34 controlling the supply of water through the common supply pipe 33 to the header tube 31 is energized only during the period of the freezing cycle.

An exemplary electrical control circuit for the refrigeration system is shown in FIGURE 6, the motor for compressor 10 being controlled by relay 18R whose coil is under control of conventional high and low pressure safety relay contacts 60, pressure fail switch controls 61 and built in overload contacts 62, all of which are conventional. The motor for water pump 34 is under control of relay 34R whose coil is coupled in this embodiment through contacts of a hand operated auxiliary switch 63 and the movable contact 56a controlled by the cam of timer mechanism 5-5 to complete the circuit to stationary contact 56]) and energize the pump 34 only during the freezing cycle. Stationary contact 56:: establishes the supply through movable contact 56a to solenoid valve 17 to open this valve and to energize relay 54R controlling the screw conveyor drive motor 54 only during the harvesting cycle.

A conventional timer 57 connected in series with the oil return solenoid valve 29 also periodically energizes this solenoid to return oil through the conduit 28 as previously described.

The purpose of the hand operated auxiliary switch 53 is to permit completion of the supply circuit through the water pump control relay 34R to pump water to the spray nozzles 32 only when it is desired to wash down the evaporator surfaces 40, 41.

While only two conduits 2t) and injector tubes 22 are shown in FIGURES 1, 4 and 5, it will be appreciated that as many such conduits and injector tubes may be used as are desirable for the size of the evaporator in a given installation and that their location can be altered as desired.

The ice making machine illustrated in FIGURES 7 and 8 is similar to the apparatus previously described, except that the conveyor-crusher assembly is displaced by a simple conveyor and the evaporator is designed to produce ice cubes or blocks having the configuration of a frustrum of a pyramid. The components of the machine of FIGURES 7 and 8 which are identical to those of the FIGURES 1-6 embodiment are designated by the same reference characters. evaporator 70 is provided with two ice-forming surfaces 71, 72 of large area formed for example by metallic side plates whose means planes are in vertical parallelism, and which are provided with a plurality of adjoining or closely adjacent recessed cells 73 of frustopyramidal configuration, opening outwardly of the ice-forming surfaces. The inclination of the sides of the recessed cells is such that water sprayed onto the upper portions of the surfaces 71, 72 will readily migrate downwardly along these surfaces and build up ice blocks, indicated at 74 in FIGURE 9, which eventually fill the cells and conform to their configuration, and will adhere to the surfaces 71, 72 during the freezing cycle due to the frost bond which inherently develops. The slope of the sides of the cells 73 is such, however, that upon disruption of the frost bond during the harvesting cycle, the gravitational forces on the ice blocks 74 will overcome whatever frictional forces may tend to retain the ice blocks in the cells. Dislodgement of the ice blocks during the harvesting cycle may be facilitated, if desired, by conventional vibrator means for imparting some small vibration or impact shocks to the evaporator. Preferably the upper and lower end portions of the evaporator side plates forming surfaces 71, 72 are shaped to provide horizontal upper and lower manifold chambers 75, '76 which communicate through the network of vertical and horizontal passages 77 defined by the adjacent sides such as sides 78, 79 of FIGURE 8, of the adjoining cells 73 converging outwardly of the sur faces 71, 72 to distribute the liquid and gas phase refrigerant throughout the evaporator in intimate thermal exchange with the cells 73. While the bases 80 of the corresponding cells 73 in the side plates are shown in direct contact with each other, it will be appreciated that they may be spaced slightly from each other if desired.

Since the FIGURE 7 apparatus is designed to produce block ice rather than crushed ice, it is unnecessary to provide an ice crushing type of conveyor as the screw conveyor of the FIGURE 1 embodiment. Accordingly a simple endless belt or endless screen conveyor 81 is provided below the evaporator 70, comprising an endless web 82 running in an upwardly opening trough 83 about rotatable cylinders 84, 85, the cylinder 85 being driven through a chain sprocket drive 86, from conveyor motor 54' like the motor 54 of the first embodiment. The operation of the refrigeration system of the FIGURE 7 apparatus is the same as the previously described ice making machine of FIGURES l6.

Alternatively, an inclined grid surface 90, as shown in FIGURES l0 and 11, may be provided below the In this modified form, the

7 evaporator 70, to direct the dislodged ice cubes or blocks laterally and downwardly into an ice chute 91 to convey the ice to a suitable storage bin below the frame 35. The grid surface 90 maybe formed of a plurality of parallel grid elements or wires 92 spaced relative to each other so as to provide water passages therebetween which are narrower than the ice cubes or blocks, thus diverting the falling ice into the chute 91 while permitting water to fall therethrough into the water pan 93. A splash baffle 94 supported from the front end of the grid structure 90 and from the grid mounting member 95 effects flowing of the spray water back into the pan 93 without producing such splashing as would cause water to splash or spill over from pan 93 into the chute 91. A water pump 34' corresponding functionally to water pump 34 circulates the spray water from the pan 93 to the headers 31 and spray nozzles 32. Water required to replenish that lost due to freezing of ice is supplied to the pan 93 through inlet pipe 96 controlled by float valve 97 which regulates the inlet 96 in accordance with the water level in pan 93.

It Will be apparent that with each of the refrigeration systems described, once the system is properly charged 1 with refrigerant, the evaporator will be cycled back and forth between freezing mode and harvesting mode simply by closing and opening the solenoid valve 17. This produces either lower pressure conditions in the evaporator and accumulator when the valve 17 is closed, causing evaporation of refrigerant and consequent freezing of water, or higher pressure conditions in the evaporator when the valve 17 is open and liquid refrigerant is supplied to the evaporator, causing rejection of heat due to the return of liquid refrigerant and some condensation and consequent thawing of the frost bond holding the ice to the external evaporator surfaces. Considerable simplification and improvement in reliability of operation of the refrigeration system is thus achieved, with significant efficiency of operation and without the troublesome, problems attendant to thermostatic expansion valves conventionally used to meter liquid refrigerant flow to a low pressure evaporator to produce freezing in typical refrigeration systems.

While several modifications of the present invention have been particularly shown and described, it will be apparent that various modifications may be made Within the spirit and scope of the invention, and it is desired, therefore, that only such limitations be placed on the invention as are imposed by the prior art and set forth in the appended claims.

What is claimed is:

1. In ice making apparatus, a refrigeration system adapted to be cycled alternately through a freezing cycle and a harvesting cycle, including an enclosed evaporator chamber adapted to be full of liquid refrigerant at the commencement of the freezing cycle having two heat conducting, generally vertically disposed side walls defining exterior ice-forming surfaces of large area, Water spray means for directing Wateronto said ice-forming surfaces adjacent the top thereof during said freezing cycle, said evaporator chamber having a liquid refrigerant inlet connection and a suction outlet connection, means for continuously applying suction conditions to said outlet connection of said evaponator chamber throughout both said freezing and harvesting cycles, and valve means for placing said evaporator chamber in closed inlet condition during said freezing cycle to terminate all supply of liquid refrigerant thereto, said valve means closing said inlet connection during said freezing cycle to establish reducing pressure conditions during the freezing cycle responsive to the suction conditions continuously applied to said outlet connection causing evaporation of liquid refrigerant therein in thermal exchange with water on said ice-formin g surfaces to freeze the same in frost bonded relation on said surfaces, said valve means opening said inlet connection to deliver liquid refrigerant therethrough to effect filling of said chamber with liquid refrigerantand condensation of gaseous phase refrigerant therein during the harvesting cycle causing thawing of the frost bond and discharge of ice therefrom.

2. Ice making apparatus as defined in claim 1, wherein said evaporator chamber comprises horizontally elongated, vertically spaced top and bottom manifold chamber means and a plurality of axially elongated hollow vertical tubular members of rectangular cross-section extending therebetween secured in side-by-side abutment with their axes arranged in vertical parallelism in a common vertical plane whereby two corresponding sides of said tubular members lie in a pair of laterally spaced vertical planes and define said pair of ice-forming surfaces.

3. Ice making apparatus as defined in claim 1, wherein said ice-forming surfaces are formed by a pair of wall members having a plurality of recessed cells of substantially frusto-pyramidal configuration disposed closely adjacent each other in a pattern substantially covering the areas of said surfaces.

4. Ice making apparatus as defined in claim 1, wherein said ice-forming surfaces are formed by a pair of wall members having a plurality of recessed cells of substantially frusto-pyramidal configuration disposed closely adjacent each other in a pattern substantially covering the areas of said surfaces, the base surfaces of said cells being disposed adjacent a medial vertical plane through said evaporator chamber with corresponding base surfaces of corresponding cells in both wall members in contact with each other and the remaining portions of the corresponding cells of the respective wall members being spaced from each other transversely of the chamber defining a network of vertical and horizontal refrigerant passages in said chamber.

5. In ice making apparatus, a refrigeration system adapted to be cycled alternately through a freezing cycle and a harvesting cycle, including an enclosed evaporator chamber adapted to be full of liquid refrigerant at the commencement of the freezing cycle having two heat conducting, generally vertically disposed side walls defining exterior ice-forming surfaces of large area, water spray means for directing Water onto said ice-forming surfaces adjacent the top thereof during said freezing cycle, accumulator tank means having a conduit connection means with, said evaporator chamber for transfer of liquid phase and gaseous phase refrigerant therebetween, condenser means coupled by a valved supply conduit to said evaporator chamber to supply liquid refrigerant to said evaporator chamber only during said harvesting cycle to produce rising pressure conditions therein and thaw frost bond adhering ice to said ice-forming surfaces to dislodge the ice therefrom by thermal interchange of said ice-forming surfaces with said evaporator chamber, and means for continuously applying suction to said accumulator tank means during said freezing cycle and said harvesting cycle to reduce pressure in said evaporator chamber during said freezing cycle causing evaporation of liquid refrigerant therein without additional supply of liquid refrigerant thereto and to cause filling of said evaporator chamber with liquid refrigerant from said condenser means during said harvesting cycle and effect thawing of the frost bond to dislodge ice from said ice-forming surfaces.

6. In ice making apparatus, a refrigeration system compressor means, condenser means connected to said compressor means, receiver means for storing liquid refrigerant condensed by said condenser means, a liquid refrigerant supply conduit coupled from said receiver means to said evaporator having valve means therein, a continuously open suction conduit between said accumulator tank means and said compressor means, and means for cycling said valve means between closed and open condition for establishing the freezing and harvesting cycles respectively to prevent passage of liquid refrigerant from said receiver means to said evaporator chamber during said freezing cycle while reducing the pressure in said evaporator through said suction conduit to a level causing evaporation of refrigerant in said chamber to freeze water on said surfaces, said supply conduit admit ting liquid refrigerant from said receiver means to said evaporator chamber when said vave means is open during said harvesting cycle to fill the same and establishing pressure conditions therein causing rejection of heat through said ice-forming surfaces to release ice from said surfaces for gravitational discharge therefrom.

7. Ice making apparatus as defined in claim 6, wherein said suction conduit includes heat exchanger means placing gaseous refrigerant being withdrawn therethrough to said compressor means in heat exchange relation to said supply conduit to impart heat to liquid refrigerant flowing through said supply conduit to said evaporator chamber during the harvesting cycle.

8. In ice making apparatus as defined in claim 7, said accumulator tank means being located at a higher level than the top of said evaporator chamber and having a bottom wall and a top wall spaced sufficiently above the bottom wall to provide a gaseous phase refrigerant zone above the maximum liquid refrigerant level attained therein, said conduit connection means between said evaporator chamber and said accumulator tank means comprising conduits having vertical portions rising through said bottom wall and terminating in open ends located in said gaseous vapor zone, said conduit vertical portions having orifices immediately above said bottom. wall for admission of liquid refrigerant from said accumulator tank means into said conduit for gravitational flow therethrough to said evaporator chamber.

References Cited by the Examiner UNITED STATES PATENTS 2,637,177 5/ 1953 Reedall.

2,739,457 3/1956 Chapman 62-348 X 2,997,861 8/1961 Kocher et al 62347 3,036,443 5/ 1962 Trepaud 62-352 3,062,018 11/1962 Baker 62352 X 3,146,610 9/1964 Lowe 62-347 ROBERT A. OLEARY, Primary Examiner.

W. E. WAYNER, Assistant Examiner. 

1. IN ICE MAKING APPARATUS, A REFRIGERATION SYSTEM ADAPTED TO BE CYCLED ALTERNATELY THROUGH A FREEZING CYCLE AND A HARVESTING CYCLE, INCLUDING AN ENCLOSED EVAPORATOR CHAMBER ADAPTED TO BE FULL OF LIQUID REFRIGERANT AT THE COMMENCEMENT OF THE FREEZING CYCLE HAVING TWO HEAT CONDUCTING, GENERALLY VERTICALLY DISPOSED SIDE WALLS DEFINING EXTERIOR ICE-FORMING SURFACES OF LARGE AREA, WATER SPRAY MEANS FOR DIRECTING WATER ONTO SAID ICE-FORMING SURFACES ADJACENT THE TOP THEREOF DURING SAID FREEZING CYCLE, SAID EVAPORATOR CHAMBER HAVING A LIQUID REFRIGERANT INLET CONNECTION AND A SUCTION OUTLET CONNECTION, MEANS FOR CONTINUOUSLY APPLYING SUCTION CONDITIONS TO SAID OUTLET CONNECTION OF SAID EVAPORATOR CHAMBER THROUGHOUT BOTH SAID FREEZING AND HARVESTING CYCLES, AND VALVE MEANS FOR PLACING SAID EVAPORATOR CHAMBER IN CLOSED INLET CONDITION DURING SAID FREEZING CYCLE TO TERMINATE ALL SUPPLY OF LIQUID REFRIGERANT THRETO, SAID VALVE MEANS CLOSING SAID INLET CONNECTION DURING SAID FREEZING CYCLE TO ESTABLISH REDUCING PRESSURE CONDITIONS DURING THE FREEZING CYCLES RESPONSIVE TO THE SUCTION CONDITIONS CONTINUOUSLY APPLIED TO SAID OUTLET CONNECTION CAUSING EVAPORATION OF LIQUID REFRIGERANT THEREIN IN THERMAL EXCHANGE WITH WATER ON SAID ICE-FORMING 